Added parameter index to managed marshal variables

src/Generator/Types/Std/Stdlib.cs

@@ -98,7 +98,7 @@ namespace CppSharp.Types.Std
             var c_str = basicString.Methods.First(m => m.OriginalName == "c_str");
             var typePrinter = new CSharpTypePrinter(ctx.Context);
             string qualifiedBasicString = GetQualifiedBasicString(basicString);
-            const string varBasicString = "__basicStringRet";
+            string varBasicString = $"__basicStringRet{ctx.ParameterIndex}";
             ctx.Before.WriteLine($@"var {varBasicString} = {
                 basicString.Visit(typePrinter)}.{Helpers.CreateInstanceIdentifier}({
                 ctx.ReturnVarName});");
@@ -109,7 +109,7 @@ namespace CppSharp.Types.Std
             }
             else
             {
-                const string varString = "__stringRet";
+                string varString = $"__stringRet{ctx.ParameterIndex}";
                 ctx.Before.WriteLine($@"var {varString} = {
                     qualifiedBasicString}Extensions.{c_str.Name}({varBasicString});");
                 ctx.Before.WriteLine($"{varBasicString}.Dispose(false);");

tests/Common/Common.Tests.cs

@@ -804,7 +804,7 @@ This is a very long string. This is a very long string. This is a very long stri
     {
         using (var VirtFuncWithStringParam = new ImplementsVirtualFunctionsWithStringParams())
         {
-            VirtFuncWithStringParam.PureVirtualFunctionWithStringParams("anyRandomString");
+            VirtFuncWithStringParam.PureVirtualFunctionWithStringParams("anyRandomString1", "anyRandomString2");
             Assert.That(VirtFuncWithStringParam.VirtualFunctionWithStringParam("anyRandomString").Equals(5));
         }
     }

tests/Common/Common.cpp

@@ -901,7 +901,7 @@ ImplementsVirtualFunctionsWithStringParams::~ImplementsVirtualFunctionsWithStrin
 {
 }
 
-void ImplementsVirtualFunctionsWithStringParams::PureVirtualFunctionWithStringParams(std::string testString)
+void ImplementsVirtualFunctionsWithStringParams::PureVirtualFunctionWithStringParams(std::string testString1, std::string testString2)
 {
 }
 

tests/Common/Common.h

@@ -1336,7 +1336,7 @@ class DLL_API HasVirtualFunctionsWithStringParams
 public:
     HasVirtualFunctionsWithStringParams();
     ~HasVirtualFunctionsWithStringParams();
-    virtual void PureVirtualFunctionWithStringParams(std::string testString) = 0;
+    virtual void PureVirtualFunctionWithStringParams(std::string testString1, std::string testString2) = 0;
     virtual int VirtualFunctionWithStringParam(std::string testString);
 };
 
@@ -1345,7 +1345,7 @@ class DLL_API ImplementsVirtualFunctionsWithStringParams : public HasVirtualFunc
 public:
     ImplementsVirtualFunctionsWithStringParams();
     ~ImplementsVirtualFunctionsWithStringParams();
-    virtual void PureVirtualFunctionWithStringParams(std::string testString);
+    virtual void PureVirtualFunctionWithStringParams(std::string testString1, std::string testString2);
 };
 
 class DLL_API HasVirtualFunctionWithBoolParams